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P0128 2003 Infiniti G35 Code - Thermostat Function

Quick Answer

The P0128 code on a 2003 Infiniti G35 indicates an issue with the thermostat function in the vehicle's cooling system. Common causes include Faulty thermostat, Low coolant level, Coolant temperature sensor malfunction. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0128 2003 Infiniti G35 indicates Thermostat Function.
Common causes
Common causes include Faulty thermostat, Low coolant level, Coolant temperature sensor malfunction.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 14, 2024
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Code P0128 2003 Infiniti G35 Description

The P0128 code on a 2003 Infiniti G35 indicates an issue with the thermostat function in the vehicle's cooling system. The thermostat is a crucial component that regulates the engine's operating temperature by controlling the flow of coolant through the engine. When the engine is cold, the thermostat remains closed to allow it to warm up quickly. Once the engine reaches the optimal temperature, the thermostat opens to allow coolant to circulate and maintain a stable temperature.

OBDII Code P0128 2003 Infiniti G35 - Thermostat Function
P0128 2003 Infiniti G35 Code - Thermostat Function

Common Causes of P0128 2003 Infiniti G35

  1. Faulty thermostat
  2. Low coolant level
  3. Coolant temperature sensor malfunction
  4. Coolant leaks
  5. Clogged radiator

Symptoms of P0128 2003 Infiniti G35

  1. Engine running colder than normal
  2. Decreased fuel efficiency
  3. Check Engine Light illuminated
  4. Poor heater performance
  5. Engine overheating in extreme cases

How to Fix P0128 2003 Infiniti G35

  1. Diagnostic: Use an OBD-II scanner to confirm the P0128 code and check for any other related codes.
  2. Thermostat Replacement: Drain the coolant, remove the old thermostat, and install a new one. Ensure proper installation and refill the coolant system.
  3. Coolant Flush: Perform a coolant flush to remove any contaminants and ensure proper coolant circulation.
  4. Check Coolant Level: Verify the coolant level is correct and there are no leaks in the system.
  5. Clear Codes: Clear the diagnostic trouble codes from the vehicle's computer to reset the Check Engine Light.

Cost to Fix P0128 2003 Infiniti G35

The cost of repairing a P0128 code on a 2003 Infiniti G35 can vary depending on the specific cause of the issue. Generally, the cost of a thermostat replacement and coolant flush can range from $150 to $300, including parts and labor. Additional costs may apply if there are other underlying issues that need to be addressed. It's recommended to consult with a qualified mechanic to get an accurate estimate based on your vehicle's specific needs. Labor rates at auto repair shops typically range from $80 to $150 per hour, but can vary based on location and other factors.

What does this mean?

Tech Notes for P0128 2003 Infiniti G35

If cooling system is not leaking and the fluid level is OK, replacing the thermostat usually takes care of the problem.

When is the Code Detected?

The engine coolant temperature does not reach to specified temperature even though the engine has run long enough.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0128 2003 Infiniti G35 Code

1. What does OBDII code P0128 indicate in a 2003 Infiniti G35?

- OBDII code P0128 in a 2003 Infiniti G35 typically indicates an issue with the thermostat.

2. What are the common symptoms of a P0128 code in a 2003 Infiniti G35?

- Common symptoms of a P0128 code include the engine running colder than normal, the temperature gauge not reaching operating temperature, and a decrease in fuel efficiency.

3. What are the potential causes of a P0128 code in a 2003 Infiniti G35?

- The potential causes of a P0128 code can include a malfunctioning thermostat, a faulty coolant temperature sensor, low coolant levels, or a problem with the cooling system.

4. How can I diagnose a P0128 code in my 2003 Infiniti G35?

- To diagnose a P0128 code, you can start by checking the coolant level, inspecting the thermostat for proper operation, testing the coolant temperature sensor, and ensuring there are no leaks in the cooling system.

5. Can I continue driving my 2003 Infiniti G35 with a P0128 code?

- It is not recommended to drive your vehicle with a P0128 code as it can lead to engine overheating and potential damage. It is best to address the issue promptly.

6. How can I repair a P0128 code in my 2003 Infiniti G35?

- The most common repair for a P0128 code involves replacing the thermostat with a new one. It is also advisable to check and replace the coolant temperature sensor if needed.

7. Are there any DIY tips for fixing a P0128 code in a 2003 Infiniti G35?

- While replacing the thermostat can be a straightforward DIY task for some, it is recommended to follow the manufacturer's instructions or seek professional help to ensure proper installation and avoid complications.

8. Will resetting the OBDII system clear a P0128 code in a 2003 Infiniti G35?

- Resetting the OBDII system may temporarily clear the code, but if the underlying issue causing the P0128 code is not addressed, it is likely to reappear. It is crucial to diagnose and fix the root cause of the problem.

9. How much does it cost to repair a P0128 code in a 2003 Infiniti G35?

- The cost of repairing a P0128 code in a 2003 Infiniti G35 can vary depending on the specific cause of the issue, the parts needed, and whether you choose to do the repairs yourself or take your vehicle to a mechanic.

10. Can a P0128 code affect the overall performance of a 2003 Infiniti G35?

- Yes, a P0128 code can impact the overall performance of your vehicle by causing inefficient fuel combustion, reduced engine efficiency, and potentially triggering the check engine light.

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